It is generally known to utilize longitudinal conveyors and rakes for feeding weft inlay threads to the knitting instrumentalities of a warp knitting machine in parallel relationship and at a consistent distance relative to each other, as disclosed in U.S. Pat. No. 3,564,872. A weft carriage feeds an array of weft threads with each transverse movement across the machine so that individual consecutive arrays consist of equally spaced weft threads. The desired equal distance between all threads is obtained by the rake taking over the array of weft threads at the end of each transversal movement of the weft carriage outside of the longitudinal conveyors by imparting a racking movement to the rake in the opposite direction of the direction of travel of the longitudinal conveyors at the end of each transversal movement of the weft carriage. The array of weft threads is transferred from the rake to the longitudinal conveyor when the rake moves to the racking position. The movement of the weft carriage and the rack is coordinated with the movement of the longitudinal conveyor so that the stroke and speed of movement of the rake accurately matches the corresponding movement of the longitudinal conveyor. In the aforesaid U.S. patent this coordination of movement is accomplished with the aid of a cam which rotates in synchronism with the continuously running longitudinal conveyor.
This type of timing cam is expensive to manufacture. Also, the timing cam must be changed when the width of the array of weft threads is altered. In particular situations where several weft carriers are used, as disclosed in DE-OS No. 3 343 048, the timing cam must have its own drive. In these instances where two cams are required for each weft carriage, each timing cam must be provided with its own drive so that this arrangement necessitates a very expensive construction.